Science and Treatment Need to Look at the Big Picture

Even with the best care available, current treatments for mental illness are not up to the task, according to National Institute of Mental Health Director Thomas Insel, M.D.

While there have been some breakthroughs in the understanding of mental illness in recent years, Insel believes there is still a great deal of research that needs to be done to understand the causes of mental illness, predict risk factors and develop effective treatments and early interventions that will consistently help people with these diseases.

Insel spoke at the NAMI national convention earlier this month, along with National Institute on Drug Abuse (NIDA) Director Nora Volkow, M.D.

Volkow’s message was equally sobering: while we have a lot to learn about the co-morbidity of mental illness and substance abuse disorders, we do know that people with mental illnesses are much more likely to abuse substances, and vice versa.

We also know that substance abuse compounds the increased mortality associated with mental illness. Volkow laid out areas where future research is needed, but emphasized the importance of cautioning children and teens against drug use--for those with certain risk factors, using drugs can be disastrous.

Mental illnesses are developmental, Dr. Insel noted, in the sense that changes occur in the brain long before behavioral changes. He shared results from recent studies that show that differences appear in the brains of people with Alzheimer’s disease in their teens, decades before the onset of symptoms. A similar process may take place in people with schizophrenia.

Studies have shown that close monitoring of people who have precursor symptoms to schizophrenia (also called “prodromal” symptoms) has made it possible for doctors to predict who will have psychosis before the onset of psychotic symptoms. Dr. Insel’s hope is that this research, along with other research into the genetic risk factors of mental illnesses, will some day make it possible to intervene early in the course of disease, or even take steps to prevent it.

Dr. Volkow warned that medical research ignores the close link between mental illness and substance abuse at its peril. The co-existence of mental illness and substance abuse may give clues into causes of both disorders. Genetic, developmental, and environmental risk factors for mental illness and substance abuse ultimately overlap.

Volkow recounted a study of the effects of marijuana on the neurotransmitter dopamine. While the brain is still forming during adolescence, smoking marijuana appears to alter dopamine-producing cells, making them more sensitive and harder to “turn off.” At the same time, other studies show that psychosis is associated with excess dopamine, suggesting that marijuana smoking during adolescence, combined with genetic susceptibility, increases risk of onset of schizophrenia.

Dopamine may also be one reason why rates of smoking are higher among people with mental illnesses--nicotine prevents the breakdown of dopamine, creating an antidepressant effect.The rate that a person is smoking at age 18 may in fact also serve as a predictor for their risk of schizophrenia.

Substance abuse also compounds the risks of death and disease associated with serious mental illness, Volkow reported.For example, while a person with psychosis has an elevated risk of heart disease, a person with both psychosis and substance abuse has an even greater risk of developing the disease.

Substance abuse and mental illness often go hand in hand, and the combination can be deadly.